1. Field of the Invention
The present invention relates to a nonaqueous electrolyte battery, a battery pack comprising the nonaqueous electrolyte batteries, and a vehicle having the battery pack mounted thereto.
2. Description of the Related Art
A nonaqueous electrolyte battery comprising a negative electrode containing a lithium metal, a lithium alloy, a lithium compound or a carbonaceous material attracts attentions as a battery having a high energy density, and a vigorous research is being conducted on the particular nonaqueous electrolyte battery. A lithium ion battery comprising a positive electrode containing LiCoO2 or LiMn2O4 as an active material and a negative electrode containing a carbonaceous material capable of absorbing-releasing lithium has been widely put to the practical use. Also, it is studied to use a metal oxide or an alloy in place of the carbonaceous material in the negative electrode. Where such a nonaqueous electrolyte battery is mounted to a vehicle such as an automobile, the nonaqueous electrolyte battery is required to exhibit a high performance even in the cold region and, thus, is required to exhibit a high output performance and a long cycle life performance under a low temperature environment of −20° C. or lower.
Disclosed in Japanese Patent Disclosure (Kokai) No. 2004-221523 is an electrochemical capacitor. It is taught that a lithium-titanium oxide having a ramsdellite crystal structure is used in the negative electrode of the electrochemical capacitor, and that the ratio of the electric capacity of the negative electrode to that of the positive electrode, i.e., negative electrode electric capacity/positive electrode electric capacity, is 1 to 7 in the electrochemical capacitor.